Ball-mill.



C. L. GARMAN.

BALL MILL.

APPLICATION FILED JUNE 21, 1912.

Patented Jan. 27, 1914 G. L. GARMAN.

BALL MILL.

APPLICATION FILED JUNE 21, 1912. 1,085,109. Patented Jan 27, 1914.

2 SHEETS-SHEET 2.

Si, g'd '7 6 v5 I a Ajfi\ 5 155- 4 56 i 55" I I l I 1 I I CHARLES LEWIS CARMAN, 0F RIVERSIDE, CALIFORNIA.

BALL-MILL.

Specification of Letters Patent.

Patented Jan. 27, 1914.

Application filed June 21, 1912. Serial No. 705,007.

To all whom it may concern:

Be it known that I, CHARLES LnwIs CAR- MAN, a citizen of the United States, residing at Riverside, in the county of Riverside and State of California, have invented certain new and useful Improvements in Ball-Mills, of which the following is a specification, reference being made to the accompanying drawings.

My present invention relates to grinding machines in general, and more particularly to an improved arrangement of screening surfaces in a ball mill.

The principal objects of this invention is the provision in a grinding machine of a series of screening surfaces provided with intercommunicating means whereby the screening efficiency of the machine is increased; the provision of cooperating screening surfaces arranged in sections and provided with means of communication there between designed to furnish an increased area of screening surface to the pulverized material; the provision of a novel arrangement of communicating ports or channels adapted to cooperate with screening surfaces and subjecting the material to additional screening surfaces until the fine material is fully screened out and discharged, the coarser material being returned to the grinding chamber for further pulverization; the provision of a screening surface in a grinding machine which is readily removable therefrom for the purpose of repairs and the like; and in general the provision of an improved form or grinding machine in' which the area of effectual screening surface is materially augmented without appreciably adding to the power required to drive the mill, and Without detracting from the wieldiness of the machine, resulting in an economical and compact construction adapted to increase and equalize the screening and grinding capacities of an apparatus such as described above.

These and such other objects as may hereinafter appear or are incidental to my invention I attain by means of a construction illustrated in preferred form in the accompanying drawings, wherein Figure l is a cross sectional view through a grinding machine embodying my invention.

Figure 2 is a section on the line IL-II of Figure 1.

Figure 3 is an enlarged detailed drawing on the line III-III of Figure 2, being a section through one of the cross-over ports.

It is well known that in the usual types of a machine of the class described the screening capacity is approximately one-half of the grinding capacity, particularly so when the product must necessarily reach a high degree of fineness as for example in the manufacture of Portland cement. The inequality of capacities is due mainly to the inability to increase the area of screen surface without adding tothe unwieldiness of a machine already carrying an unbalanced load, as is the case of the ball mass used in this type of machine.

By my novel and compact arrangement of screens and communicating cross-over ports these objectionable features are eifec tually overcome, and at the same time the effective screening capacity is considerably increased and rendered proportionate to the grinding capacity ofthe machine without appreciably adding to the power required to drive it.

Referring now more particularly to the drawings illustrating my preferred con? struction, it will be seen that I provide a perforated drum shell or cylinder 4 secured to the drum heads 5, which latter are secured upon a centrally located shaft 6 adapted upon being rotated to revolve in suitable bearings 7 which are mounted upon standards 8. The drum is inclosed by a housing 9 which is provided with an outlet opening 10 leading to any suitable conveying means. A feed inlet opening 11 leading to the grinding chamber 12 is provided in the housing 9 and one of the heads 5 and preferably located about the shaft.

Secured to the drum heads 5 by the plates 13 and bolts 14 and bearing upon the outer edges of the drum shell 4 are annular flanges 15 to which are in turn fastened a primary screening surface or fore-screen 16, an inner finishing screen 17, a solid gathering plate 18, and an outer peripheral finishing screen 19, preferably arranged concentric in the order named and as disclosed in Figures 1 and 2, providing spaces A, B and C respectively for the passage of the pulverized product.

' plates and ball mass.

Positioned within the drum are eccentrically arranged grinding plates 20 removably held in position by means of retaining clips 21 and bolts 22, more fully described and claimed in a copending application thereon for United States Letters Patent.

Extending longitudinally the drum and transversely from forescreen to outer screen is one or more cross-over chambers or boxes 23 dividing the screening surfaces into sections and to which the screens are fastened, said chambers being provided with a top plate 24 and. a bottom plate 25, means of communication being afforded by a plurality of ports or conduits A, B, and C opening to the top plate 24. The ports A diagonally connect the space A which extends between the forescreen 16 and the inner screen 17 in one section with the space 0 between the gathering plate 18 and outer screen 19 in another sectionythe ports B provide channels from the space B which exists between the inner screen 17 and the solid plate 18 leading to the exterior of the drum; and the ports C provide a means of communication from the space C to the interior of the drum 4. The ports C cross over from the exterior space C inwardly and provide a clear passage into the grinding 'chamber 12 and the ports A and B cross over in an opposite and outwardly direction so that the openings of the orts A and B in the top plate 24 are in t e same plane, the said ports being positioned alternately with respect to the ports C throughout the cross: over chamber 23.

The chamber 23 is further provided with an inwardly projecting scoop 26 extending to the perforated shell 4, by means of which oversize material is returned through the apertures therein to the grinding chamber to be reground.

The operation of the apparatus is substantially as follows: Rotation having been imparted to the drum through the shaft, material is then fed by any suitable means through the inlet opening 11 leading to the grinding chamber 12. The material is then cascaded and subjected to the bombardment of the balls and to the wearing action of the The ground product falls through the apertures in the drum shell 4 to the forescreen 16, rejections from the forescreen being promptly returned to the grinding chamber by the inwardly projecting scoop 26 and the finer material working through thepreliminary screen 16 is received into the space A and caught by the inner fine screen 17. A portion of the product 1n the space A which has reached the required degree of fineness for the purpose in view, works through the inner fine screen into the space B and is held by the solid gathering plate 18. As the mill revolves in the direction indicated by the arrow in Figure 1, the fines in space B gravitate to the cross-over chamber and are deflected in an outwardly direction by the port B toward the hopper outlet 10. The other portion of the fines together with the residue in the space A are deflected through the port A in the crossover chamber into the space C in the adj oining section. Additional screening surface is thus afforded the material, the outer fine screen 19 taking care of any fines which then fall into the outlet 10 and rejections from both fine screens 17 and 19 which remain in the space C being promptly returned by the port C in the adjacent cross-over chamber into the grinding chamber 12 for further pulverization.

Should occasion require the removal of the screens the bolts 14 and 22 maybe loosened up and the entire screening mechanism can then be removed intact.

In my preferred construction I show four cross-over chambers applied to a grinding mill which not only tends to preserve the balance of the machine but also increases the screening efiiciency permitting the fines to be fully screened out. It is obvious that a greater or less number of these chambers may be used in connection with a machine if desired and yet be entirely within the scope of this invention,

The entire arrangement of parts is simple and compact, and owing to the increased screening surface afforded, the output of the machines is consequently doubled. Other advantages will occur to those skilled in the art.

Having thus described my invention and illustrated its use what I claim as new and desire to secure by Letters Patent is the following 1. In a mill of the class described,a grinding chamber, a plurality of screening members arranged in series about the grinding chamber, a conduit between an inner screening member and a peripheral screening member, and a second conduit independent of the first mentioned conduit having its inlet communicating with an intermediate screening member and with its outlet opening outwardly in the said peripheral member, sub stantially as described.

2. A grinding mill comprising in combination a grinding chamber mounted for rotationabout a substantially horizontal axis, three screens around the chamber arranged one within another and spaced apart to pro vide arcuate peripheral chambers, and a cross-over box between the ends of the peripheral chambers and having a passage connecting the chamber between the inner and intermediate screens with the chamber between the intermediate and outer screens.

3. A grinding mill comprising in combination a grinding chamber mounted for rotation about a substantially horizontal axis, three screens around the chamber arranged one within another and spaced apart to pro vide arcuate peripheral chambers, and a cross-over box between the ends of the pe ripheral chambers and having a passage connecting the chamber between the outer and intermediate screens with the chamber between the inner screen and the grinding chamber wall.

4. A grinding mill comprising in combination a grinding chamber mounted for rotation about a substantially horizontal axis, three screens around the chamber arranged one within another and spaced apart to provide arcuate peripheral chambers, and a cross-over box between the ends of the periph eral chambers and having a passage connecting the chamber between the inner and intermediate screens with the chamber between the intermediate and outer screens and having a passage connecting the chambers between the outer and intermediate screens with the chamber between the inner screen and the grinding chamber wall.

5. In a mill of the class described, a grinding chamber, annular flanges disposed about the chamber, a plurality of screening members extending in spaced relation between the flanges, a guiding chamber within the said flanges and connecting the spaces between the screening members, and means for detachably securing the said flanges to the grinding chamber.

6. In combination, a rotary grinding chamber, an inner and an outer screen, a gathering member within the screens, and divided by a chamber disposed between the screens, the screens and gathering member being spaced apart and having their terminals extending to the wall of the chamber, independent conduits in the chamber having inlets communicating with the spaces between screensand gathering member, the said conduits being constructed and arranged so as to constitute shunting avenues for guiding material independently of each other from the said spaces to points respectively within and without the outer screen.

7. In a mill of the class described, the combination of a grinding chamber, a plurality of spaced screening members about the grinding chamber terminally separated into screening portions by one or more crossover boxes, said cross-over box having a conduit formed therein with its inlet in register with an inner screening member in one portion and with its outlet communicating with an outer screening member in the other screening portion, whereby on rotation of the mill the unscreened material from the first mentioned portion gravitates to the screen in the second mentioned portion for further screening, and means for returning rejections from the second mentioned portion operating independently of the first mentioned portion.

8. In a mill of the class described, a grinding chamber, a series of spaced screens about the grinding chamber having an interposed imperforate gathering member concentric therewith, means to separate the screens into successive discharging and screening sections including a plurality of divergingconduits interposed between the screen terminals, said conduits having their alined inlet openings independently registering with the spaces in the discharging section, one of the said conduits having its outlet leading inwardly to the grinding chamber, a second conduit having a peripheral discharge outlet leading outwardly between the sections, and a third conduit communicating with the succeeding screening section substantially as and for the purpose set forth.

9. In a mill of the class described having a grinding chamber, the combination of screening means about the grinding chamber comprising a screening section having an inner screen and a gathering member spaced apart for the passage of material, with a second screening section having another portion of the gathering member and a spaced outer screen which is peripherally about the gathering member. in both sections, means interposed between the terminals of the said sections including a conduit adapted to shunt unscreened material from the inner screen of the first section to the outer screen of the second section for further screening, means for returning the accumulated rejections of both the said inner and outer screens to the said grinding chamber, and means for discharging the screened material collected by the gathering member in the first section having an outlet opening substantially at a point intermediate the terminals of the sections.

10. In a mill of the class described, a grinding chamber, an inner and an outer screen, a gathering member within the screens, and divided by a box which provides a chamber extending radially between the inner and outer screens, the screens and gathering member being spaced apart and having their terminals extending to the walls of the box, conduits in the chamber having inlets opening in the wall of the box communicating terminally with the In testimony whereof; I have hereunto screens and gathering member, one of the signed my name in the presence of the two 10 conduits substantially forming a continuasubscribed Witnesses.

tion between an inner screen and, an outer screen; and another conduit leading from CHARLES LEWIS the gathering member and discharging ex- Witnesses:

teriorly' of the mill at a point substantially W. HERBERT FOWKES,

intermediate the screen terminals. M. H. ERICKSON. 

